Even some of vehicles have mounted with tweeters for a high frequency sound range as audio speakers in addition to woofers for a low frequency sound range. Among possible positions for mounting tweeters are portions on both widthwise sides of an upper surface of a dashboard and a base portion of a front pillar. Of these portions, mounting a tweeter on a base portion of a front pillar is desirable in a case of a sound-quality-oriented tweeter (Patent Literature 1).
Various devices such as a defroster duct and a curtain air bag are housed within a pillar trim of a front pillar (Patent Literature 2 and 3).